Feeding mechanism for sewing machines



3 N. v. CHRISTENSEN Er AL 1,947,380

FEEDING MECHANISM FOR SEWING MACHINES Filed April 16, 1930 3 Sheets-Sheet l b- 1934- N. v. CHRISTENSEN ET AL 1,947,330

FEEDING MECHANISM FOR SEWING MACHINES Filed April 16, 1930 3 Sheets-Sheet 2 o Q I (36 .39 ZZc QZ.

1m 13 l] a? 1 f; 60 4 Q Q 9 L19 6 O3 1 1" M 1934- N. v. CHRISTENSEN ET AL 1,947,380

FEEDING MECHANISM FOR SEWING MACHINES Filed April 16, 1930 3 Sheets-Sheet 3 aff' w Patented Feb. 13, 1934 UNITED STATES FEEDING MEICIIIIXANISM FOB SEWING.

INES

Norman V. Christensen and Frederick-F. Zeier,

Chicago, Ill., assignors to Union. Special: Ma chine Company; Chicago, ..Ill'., a; corporation of Illinois Application April 16, 1930; SerialNo. 444 771:

7 1 Claims. (Cl. 112-215) The invention relates to new and useful im-, provements in sewing machines, and more particularly to the feedingmechanism for a sewing machine.

. In some types of machines, it is desirable to arrange the actuating shaft above the work support so that a direct driving connection with the needle bar maybe had. An object of the present invention is to provide such a machine with 1 devices for raising and loweringa feed, dog disposed beneath the work support, whereby the feeddog is given asubstantially fiat travel duringthe feeding of the fabric.

A further object of the invention is to provide amachine of the above type with means for giving avertical reciprocation to a trimming blade from the feed dog lifting mechanism.

These and other objects will in-part be obvious and'will in partbe hereinafter morefully disclosed.

In the drawings Figure 1 is a view partly in side elevation and partly in section showing a machine embodying the improvements, the cover plates beingremoved to show the inner structure of the machine;

Fig. 2 is a view partly in front elevation and partly in section of the same;

Fig, 3; is an enlarged view insection through the connections to the eccentric strap for reciprog cating' the trimming blade and raising and lowering the feed dog, and

Fig. 4 is adiagrammatic view illustrating the pathof travel of the feed dog.

The invention is directed to a feeding mechanism for a sewing machine wherein the actuatingshaft for the feeding mechanism is located above the work support and is directly connected to the needle for actuating the same. The feed,- ing mechanism includes a feed dog carried by a feed bar locatedbeneath the work support, which i5 through a direct connection of thepart cooperating with the eccentric member; with the feed rocker. The feed dog israised'and lowered by an eccentrically arranged member'on the actuating shaft. This is accomplished through de- .50 viceswhich give to the feed dog a substantially fiat path of travel during the feeding. of the fabric. The eccentrically arranged member is connected to a studwhich is mounted on a lever sorthat the stud is moved up and down. in sub- -5 stantiallya vertical line; A link-connected to the stud isalso. connectedrto. the feed bar so that the up-and down movements of the stud impart up :and down, movements to. the; feed. bar. The stud. is located. between the actuating shaftand the:feed barand, the;link: so positioned that it 130. swings. in anarc as the feedbar moves back and forth, which: is. so disposed as to produceasubstantially flattravel'of, the feeddog at the time it;is feeding; the fabric. A trimming mechanism maybe associated w-ith-the feeding mechanism, 65. and the vertical movements for, the trimming bladeaderived from this stud-which; is moved up and down for; raisingand lowering the feed dog.

In the. drawings, the invention, is shown as embodied in amachine designed for overedging. I0. The, machine. includes a; supporting bed. 1 pro} videdwitlr upstandingmembers 2 and 3 to which the work-supportA-is attached. Securedto the work support by screws, 5,5;is; a throat, plate 6. They throat plateis provided;with slots '7 in which 76 the toothed sections 830ithe feed; dog 9 operate. The-feed dog-is usedfor moving the fabricover the work support during thestitching of the same. Thefabric is held on the;work support by apresser foot IO-carried byan arm 11 which is pivoted at; 12 to astandard I mounted on the bed. of; the machine and projecting above, the plane of the Work support. Thearm 11 carrying the presser baris moved-downward by means of a. plunger 13 mounted inthehead ofthe mar chineand pressed-downward by a spring -14. An adjusting; screw. 1515. provided to, vary the pressure exerted. bythe; spring on the plunger 13. The shank of the f ed dog9-is secured to the end ofthe feed bar: indicated at. 16 in the drawings, by ascrew. 17; Thefeed, bar-is pivoted at 18; to a feed-rocker 19. Thefeed rocker 19 ismounted for oscillation on-the supporting bed 1. Itv oscillates about an; axis 20. When the-feed rocker is oscillated; it will move thefeed bar; back and forth andthusimpart backand forth movements to-thefeeddog. Mounted on the standard 1*? is anactuating shaft 21. The actuating shaft as shown in the'drawings, is driven'by a belt wheel 22. This actuatin gshaft is well above the work support: andv isdirectly connected to the needle bar forreciprocating the same, as will hereinafterbe pointed out. Mounted on this, actuating shaft2lis an eccentricallyarrangedmember 23. This, as shown in the drawings, is in they form ofv an. eccentric. It willgbetunderstood, however, that acrank or any other. type ofi'eccentric member may be used in place of this eccentric, which has been shown merely for. the purpose of illustrating an. operating means. Cooperating with U this eccentric is an eccentric strap 2a. The ecthis movement of the link tends to lower the feed centric strap 24 is directly connected to a ball stud 25 mounted for adjustment in a slot 26 in an arm 27 which is formed integral with the feed rocker. The actuating shaft 21 is disposed at a slight angle to the line of feed and in rear of the stitching point. The eccentrically arranged member 23 is substantially directly over the arm 27 on the feed rocker, and the eccentric strap, therefore, will impart direct oscillations to the feed rocker. The adjustment of the stud in the slot 26 is in the general direction of the axis of the actuating shaft, and therefore, the stroke of the feed dog may be varied by shifting this stud without varying the timing of the feed dog. Also mounted on this actuating shaft 21 is a second eccentrically arranged member 28, which, While shown in the form of an eccentric, likewise may be in the form of a crank or any other arrangement of an eccentric part for imparting reciprocations to a member. Cooperating with this eccentric, is an eccentric strap 29. The eccentric strap 29 engages a ball head on a stud 30. This stud 30 is fixedly attached to a lever 31 which is pivoted at 32 to the standard l This lever preferably carries the movable trimming blade so that the eccentric member 28 as it raises and lowers the lever 31, will raise and lower the trimming blade. The stud 30 is connected at its outer end to a link 33 which in turn is connected at its lower end to a stud 34 fixed to the feed bar. The up and down movements imparted to the stud 30, will, through the link 33, impart the up and down movements to the feed bar. This link 33, as shown in Fig. 1, is slightly inclined to the'longitudinal axis of the eccentric strap 29. The stud 34 is slightly in advance of the stud 30. As shown in Fig. 1, the feed dog is raised, and is completing its feeding movement.

In Figure 4 of the drawings there has been illustrated on an enlarged scale certain parts of the feeding mechanism and the path of movement of a point in the feed dog. The eccentric which raises and lowers the feed dog is so timed that the feed dog is at its lowest point of movement when said feed dog is midway between the ends of its feed stroke and on its return or idle movement. As thefeed dog continues toward the forward end of its stroke the eccentric begins to lift the swinging link and lifts the feed bar. When the lifting eccentric has turned through an arc of substantially 90 degrees the feed dog has reached the extreme forward end of its stroke. It is so illustrated in the drawings and a point in the feed dog which is to be followed in the feeding movement of the dog is at a. As the feed dog starts on its feed stroke the lifting eccentric continues to lift the swinging link. The swinging link how ever is moving now toward a perpendicular and the pivotal connection between the lower end of the link and the feed bar is moving in a downward arc. Thus it is that the effective lift of the feed bar is different than the extent of lift of the eccentric which raises the swinging link. This flattens the path of travel of the feed dog. The point which we are following has moved in the path illustrated in Fig. 4 to the point b. The feed dog is now raised to its highest point of lift by the lifting eccentric which raises and lowers the swinging link. The downward movement however of the swinging link is first relatively slow as the eccentric is travelling in a circular path and the resultant vertical movement imparted thereby is comparatively small. The link is now swinging towards the vertical and while dog the path of travel of the feed dog continues relatively fiat and substantially straight until the point e is reached after which the feed dog moves downwardly more rapidly until the point (2 is reached, which is the extreme throw of the feed dog. When the feed dog is at the rear end ofits stroke the point which is being followed in its path of travel is slightly below the plane of the work support. When this point is at the forward end of the travel of the feed dog as indicated at a it is slightly above the plane of the throat plate. This is due to the fact that the link 33 is inclined at a greater angle to the vertical when at the forward end of the feed stroke than it is when at the rear end of the feed stroke. The path of movement of the point in the feed dog as the feed dog moves forward will be lowered gradually until the point e is reached as the forward movement of the feed dog swings the link so as to modify the extent to which the feed dog is lowered by the eccentric. When the point e is reached the feed dog raises quickly through the throat plate and into engagement with the fabric.

With the above it will be noted that the feed dog while in engagement with the fabric for feeding the same moves in a relatively fiat path or a substantially straight line. It will also be noted that the extent of lift imparted to the feed dog is considerably less than the vertical movement of the stud 30 in the lever which carries the trimming blade. The trimming blade is at the end of the lever 31 carrying the stud 30 and the extent of movement imparted to the trimming blade by the up and down movements of the stud 30 are considerably greater than the movement of the stud 30. Therefore the up and down movements of the trimming blade will be greater than the up and down movements of the feed dog. This enables sufficient throw to be given to the trimming blade to trim the fabric sections without necessitating abnormal up and down movements of the feed dog. Furthermore the swinging link as noted modifies the effective movement of the eccentric which is imparted to the feed dog and flattens out the path of travel of the feed dog so that it is in substantially a fiat path of movement while it is in engagement with and moving the fabric.

Mounted on the end of the lever 31 is a trimming blade 35 which cooperates with a stationary trimming blade 36 carried by the work support. This same eccentrically arranged member which raises and lowers the feed dog, reciprocates the trimming blade. By this arrangement of a link which flattens the movement of the feed dog in its path of travel, sufiicient throw may be given to the lever for imparting the desired extent of reciprocation in the trimming blade. The trimming blade is attached to the end of the lever. while the eccentric strap is attached to the lever intermediate its ends, and therefore, the throw of the stud 30 is multiplied in the reciprocations imparted to the trimming blade. The throw of the stud 30 is also modified through the swinging action of the link 33 so as to give to the feed dog a substantially flat or straight travel during the feeding of the fabric.

As shown in the drawings, the machine is designed for producing overedge stitches. The needle is indicated at 3'7, and is carried by a needle bar 38 which is directly connected by a link 39 to a crank 40 on the end of the actuating shaft 21. Cooperating with the needle is an overedge looper 41 and an under looper 42. These loopers are operated through trains of devices from eccentrics carried by the actuating shaft 21. The machine shown and described in detail is similar in many respects to the machine shown and described in Patent No. 1,751,508, granted Norman V. Christensen and Frederick F. Zeier, March 25, 1930. The arrangement of the shaft relative to the work support, the mechanism for reciprocating the feed bar, and the common devices for raising the feed dog and operating the trimming blade are claimed broadly in our prior patent. The present invention is directed particularly to this arrangement of the link which gives to the feed dog a substantially flat travel during the feeding of the fabric, and which, by this arrangement, enables the trimming blade to be given a stroke suflicient for the trimming of the fabric sections in advance of the stitching of the same. While the invention has been described in connection with a machine for forming overedge stitches, it will be understood that it may be used in connection with other types of stitching mechanisms. The essential features consist in the arrangement of the actuating shaft above the work support, and the raising and lowering of the feed dog through devices operated by said shaft, which devices are so constructed as to give a substantially flat pathof travel to the feed dog during the feeding of the fabric. While the arrangement of the shaft in the general direction of the feed at one side of the line of feed is a very desirable arrangement for the positive operating of the feed parts in a high speed machine, it will be understood that the present invention is not limited to the arrangement of the shaft as stated.

Having thus described the invention, what we claim as new and desire to secure by Letters Patent, is-

1. In a sewing machine, the combination of a work support, a shaft, a feed bar beneath the work support, a feed dog carried thereby, means actuated by said shaft for moving the feed dog back and forth, a trimming blade, means independent of the feed bar for supporting said trimming blade, and means actuated by said shaft for raising and lowering said feed dog and for imparting a substantially vertical right-line movement to said trimming blade, said lastnamed means including a member so disposed as to give to said feed dog a substantially flat path of travel during the feeding of the fabric.

2. In a sewing machine, the combination of a work support, a shaft, a feed bar beneath the work support, a feed dog carried thereby, means actuated by said shaft for moving the feed dog back and forth, a lever, a stud carried by said lever, an eccentrically arranged member on said shaft connected to said stud for raising and lowering the same, a link pivoted to said stud and to the feed bar for raising and lowering the feed bar, said link being disposed relative to the stud on the lever so that the feed dog is given substantially a flat path of travel during the feeding of the fabric.

3. In a sewing machine, the combination of a work support, a shaft, a feed bar beneath the work support, a feed dog carried thereby, means actuated by said shaft for moving the feed dog back and forth, a lever, a stud carried by said lever, an eccentrically arranged member on said shaft connected to said stud for raising and lowering the same, a link pivoted to said stud and to the feed bar for raising and lowering the feed bar, said link being disposed relative to the stud.

on the lever so that the feed dog is given substantially a flat path of travel during the feeding of the fabric, a movable trimming blade carried by said lever, and a stationary trimming blade carried by the work support with which said movable trimming blade cooperates.

4. In a sewing machine, the combination of a work support, a shaft, a feed bar beneath the work support, a feed dog carried thereby, means actuated by said shaft for moving the feed dog 88 back and forth, a lever, pivoted at its rear end and extending in the general direction of the feed bar, a stud carried by said lever, an eccentrically arranged member on said shaft, a device cooperating therewith and connected to said stud 90 for raising and lowering the same, a link pivoted to said stud and to said feed bar, said link being inclined rearwardly from the feed bar upwardly to the stud on the lever whereby the swing of the link causes said feed dog to move in substantially a flat path of travel during the feed of the fabric.

5. In a sewing machine, the combination of a work support, a shaft, a feed bar beneath the work support, a feed dog carried thereby, means actuated by said shaft for moving the feed dog back and forth, a lever pivoted at its rear end and extending in the general direction of the feed bar, a stud carried by said lever, an eccentrically arranged member on said shaft, a device cooperating therewith and connected to said stud for raising and lowering the same, a link pivoted to said stud and to said feed bar, said link being inclined rearwardly from the feed bar upwardly to the stud on the lever whereby the swing of the no link causes said feed dog to move in substantially a fiat path of travel during the feed of the fabric,

a movable trimming blade disposed in front of the feed dog and connected to the forward end of said lever, and a stationary trimming blade 11 mounted on the work support with which said movable blade cooperates.

6. In a sewing machine the combination of a work support; a shaft, a feed bar beneath the work support, a feed dog carried thereby, means 2 actuated by said shaft for moving the feed dog back and forth, and means actuated by said shaft for raising and lowering said feed dog, said lastnamed means including an eccentrically arranged member on said shaft, a stud mounted 5 for substantially vertical movement and connected to said eccentrically arranged member, a member connected to said stud and to the feed bar, said member being disposed relative to the stud so that the feed dog is given a substantially no fiat path of travel during the feeding of the fabric.

7. In a sewing machine, the combination of a work support, a shaft, a feed bar beneath the work support, a feed dog carried thereby, means actuated by said shaft for moving the feed dog back and forth, a lever mounted above the work support, a trimming blade carried by said lever, means operated from said shaft for oscillating said lever and imparting substantially vertical right-line movements to the trimming blade, and means operated by said lever and connected to said feed bar for giving to said feed dog its up and down movements, said last-named means including a member so disposed as to give to said feed dog a substantially flat path of travel during the feeding of the fabric.

NORMAN V. CHRISTENSEN. FREDERICK F. ZEIER. 

